A known device for absorbing the torque fluctuation between a drive power source such as an internal combustion engine and an electric motor and a transmission connected to wheels for transmitting the driving force from the drive power source such as engine disclosed in Japanese Patent Application No. 2002-13547 is shown in FIG. 7. As shown in FIG. 7, the device for absorbing the torque fluctuation is positioned between a drive shaft 50 of the drive power source (not shown) and an input shaft 60 of the transmission. The device for absorbing the toque fluctuation includes a flywheel 30 fixed to the drive shaft 50 on the input shaft 60 side and a damper mechanism 33 provided between the flywheel 30 and the input shaft 60 of the transmission for absorbing the torque fluctuation of the flywheel 30 to transmit to the input shaft 60. The damper mechanism 33 includes discs 33A. 33B extended in an external peripheral side, a hub 32 including a flange 32A, damper members 34A provided on a hub portion between the hub 32 and the flange 32A in radial direction, and a limiter portion 35 for interrupting the transmission of the driving force from the flywheel 30 to the hub 32 when the fluctuation torque between the damper mechanism 33 and the flywheel 30 reaches a predetermined value. The damper mechanism 33 is engaged with the flywheel 30 via the limiter portion 35. An internal peripherally of the hub 32 is connected to the input shaft 60 via splines. The damper mechanism 33 is constructed to absorb the torque fluctuation generated between the discs 33A, 33B and the flange 32A respectively. The limiter portion 35 includes a friction member 35A fixed to the external periphery of the disc, a biasing member 35B for biasing the friction member 35A towards the fly wheel 30, and a limiter plate 35C provided between the biasing member 35B land the friction member 35A.
The driving force from the drive power source is transmitted to the flywheel 30 via the drive shaft 50 and the driving force is transmitted to the discs 33A, 33B via the limiter portion 35 on the external peripheral side of the flywheel 30. When the discs 33A, 33B are rotated by the driving force transmitted to the discs 33A, 33B, the driving force is transmitted to the flange 32A via the damper members 34A. In this case, the permissible torque fluctuation of the damper members 34A is absorbed based on the absorbing characteristics of the torque by the damper members 34A and is transmitted to the input shaft 60 via the flange 32A. When a relative rotational amount between the discs 33A, 33B and the hub 32 during transmitting the driving force reaches a predetermined value, the relative rotation is regulated. When the torque fluctuation is further generated so that the torque fluctuation exceeds an allowable frictional engagement range of a frictional engagement between the fictional member 35A and the flywheel 30, the limiter portion 35 is operated so that the frictional member 35A and the hub 32 are unitarily rotated relative to the flywheel 30.
When the known device for absorbing the torque fluctuation with the foregoing construction is assembled to a vehicle, the flywheel 30 is fixed to the drive shaft 50 with bolts 42 under a condition that the flywheel 30 and the damper mechanism 33 are separated. Then, the frictional member 35A of the damper mechanism 33 is frictionally engaged with the flywheel 30 by tightening bolts 43 via the limiter plate 35C and the biasing member 35B while facing a shaft core of the damper mechanism 33 to the flywheel 30 fixed to the drive shaft 50 to install the flywheel 30 to the damper mechanism 33. By inserting the input shaft 60 into a hub 32 of the damper mechanism 33 to fit an internal periphery of the hub 32, the assembling of the known device for absorbing the torque fluctuation to the vehicle is completed.
With the construction of the known device for absorbing the torque fluctuation, the flywheel 30 cannot be assembled to the drive shaft 50 of the vehicle unless the flywheel 30 and the damper mechanism 33 are separated. Thus, when transporting the known device for absorbing the torque fluctuation before assembling to the vehicle, the flywheel 30 and the damper mechanism 33 are separated considering the assembling performance of the device for absorbing the torque fluctuation to the vehicle.
Notwithstanding, with the construction shown in FIG. 7, approximately the whole portion of the limiter portion 35 including a radial directional external peripheral surface of the limiter portion 35 is exposed to the external ambient under the condition that the flywheel 30 and the damper mechanism 33 are separated. Thus, by transporting the flywheel 30 and the damper mechanism 33 as separated parts, foreign materials such as dust are apt to be attached to the frictional member 35A of the limiter 35 during transporting the separated parts. The application of the foreign material such as dust may particularly influence on an initial frictional characteristics of the frictional member 35A. For example, this includes a drawback that the frictional characteristics of the frictional member 35A differ depending on every vehicle.
A need thus exists for a torque fluctuation absorber which is unlikely attached with an foreign material such as dust on a limiter portion during transporting the torque fluctuation absorber.